Treatment of petroleum



W. T. BRYANT.

TREATMENT 0F PETROLEUM.

APPLICATION FILED Nov. I6, IQII.

LQSBTQO Eatented Jan. W, T1922.

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WILLEM T. BRYANT, 0F SHREVEPORT, LOUISIANA, SSIGNOR 0F ONE-HALF TO EARNEST R. RATCLTFF, OF SHREVEPORT, LOUISIANA.

TREATMENT 0F PETROLEUM.

Specification o Lettersv Patent.

Application tiled. November' 16, 1917. Serial No. 202,35.

T 0 all whom it my concern.:

Be it known that l, WILLIAM T. BRYANT, a citizen of the United States, residing at Shreveport, in the parish of Caddo, and State of Louisiana, have invented certain new and useful limprovements in the Treat-l ment of'ljetroleum, of which the following is -a specification. y

This invention relates to the treatment of mineral oils and particularly to the conversion 0f such oils into hydrocarbons of lower boiling-points.

More particularly, the invention relates to the treatment of hydrocarbons containing relatively large proportions of oils of the kerosene grade, for the purpose of recov.- ering large amounts of lower-boiling hydrocarbons, notably those of the motor-fuel or gasoline type.

An object of the invention is to provide a practical and economical process which will yield an increased quantity of such lowboiling products.

Other objects andadvantages will appear -as the description proceeds.

Briefly, the process comprises vaporizing theoil under pressure at a temperature which would be usually high enough to crack the oil'but under such conditions that no substantial cracking` actually occurs, introducing pressure-steam in numerous jets along the bottom of the still to agitate the oil and otherwise stirring the oil so that by the combination of the two vigorous agitation is eected and formation and deposition of carbon is prevented, then passing the vapors rapidly through a cracking-retort under substantially the saine pressure as that employed in the vaporizing still, thereafter relieving the pressure and Aallowing the entrained carbon to become deposited and nally condensing the condensible vapors. in case crude-oil is the starting material, the vaporizing of the oil through the gasoline-cut takes place under substantially atmospheric pressure and the vapors are led directly to the condenser. `When the gasoline-content is exhausted, the passage from the still to the condenser is closed and the vapors are caused to pass through the cracking-zone, ,pressure being thereupon applied in both thestill and the cracking-retort.

The apparatus comprises briefly a still and a' connected seperate eraclnfngretort,

means for closing the connection between the still and retort and means fo-r directly Patented Janniltl), 11922.

connecting the still with the condenser when the passage between the still and retort is closed, means for heating the vaporizing-still to a.' relatively high temperature, means for vigorously agitating thev oil in the still, means for applying pressure to the vapors in the still and retort, means for relieving the pressure upon the vapors after they leave the retort and means for condensing the condensable vapors.

rllhe invention will be better understood i by reference to the accompanying drawing,

in which one form of, operating-plant is shown7 somewhat diagrammaticallv, partly in side-elevation and partly in sec',y

in the drawing, the numeral a. still which may. be of ordinary form, supplied with oil by a passes preferably through the flue of a suitable furnace 3 o'ended to heat the still l. @il is fedl to the pipe Q under a suitable head through a pipe 4 equipped with a valve 5. The still is preferably inclined slightly and the oil-supply pipe 2 is connected to the still at its lowermost point so that the contents can also be withdrawn through the ,pipe 2. For this purpose, a suitable drain-pipe 6 having a valve 7 is connected to the outer end of pipe 2, so that by closing valve 5 and opening valve 7 the still l canbe emptied.

The still 1 is equipped with a pressure` gauge 8, a safety-valve 9 and a pyrometer or other suitable temperature-measuring device 10. The dome 11 has a pipe-connec mounted for rotation in bearings 15 in the still-ends. @ne end of the ,shaft 14x extends beyond the still and has thereon a sprocket-wheel 16 which receives motion through an endless chain 17 from asprocketwheel 18 driven by an electric or other motor 19. Other means than that` described ma of course be employed for effecting rotation of the agitator 13. Close to the center of thebottom of the still l, preferably between the latter andthe agita-tor 13 and substantially elo-extensive therewith, there is eteampipe 2O haringnurneroue pertorad coil 25 whereinS the vapors are cracked. The

retort is'V preferably of the type shown and described in my copending application, Se-

. rial Number 202,384, filed Nov. 16, 1917. lt

is mounted in a furnace 26 heated by a burner 27 or other suitable means. The other end of the retort is connected to a pressure-equalizer or reservoir 28 which in turn is connected through a pressure and velocity-regulating valve 29 to a pressurerelieving chamber or pipe 30 of considerably greater cross-section than the retort-pipe. The pipe or chamber 30 connects with' a ,suitable condenser 31, The pressure-equalizing drum 28 is provided with a suitable pressure-indicator 32 and a clean-out opening and draw-off 33. The pipe 24 is provided with a valve 34 and a valved steamsupply pipe 35 may supply steam, preferably superheated, to the vapors in the pipe 24.

.A pipe 36 having a valve 37 connects the plpe 24 `in front of the valve 34 directly with the condenser, so that if valve 34 is closed and Valve 37 is opened the vapors generated in the vstill will be carried to the condenser without having to pass through the retort 25.

Each section of the retort-coil 25 is, as described in my aforementioned application, provided with an internal heating element 38, sothat the heat of the tubes is conducted to the interior of the vapor-stream and one or several or all of the sections of the retort may be provided with pyrometers or other suitable heat-measuring devices 39.

1n operating with middle-distillates or oil from which the gasoline content has been removed, the valve 37 is closed and valve 34 1s opened. Oil is run into the still 1 through L pipes 4 and 2 until the still is approximately two-thirds full and the still is heated to the v aporlzing-point of the lowest-boiling fractlons, say 700o F. During the heating-up steam is admitted to the pipes 22 and 23 under considerable pressure andthe agitator 1s set in action. Thevvaporsggenerated in the still together with stearnfftfpass through pipes 12 and l24 to the retort 25.` The latter has 1n the meantime been heated to say u 850 F., a little steam being allowed) to flow` through the. retort-coil -25 meanwhile to lrotect the pipes and prevent burning. he

' the distillation.

ture of from 800 F. to 850 F. rl`he temperature of the retort may also be gradually raised until the vapors therein reach a temperature of 10000 F. or more. The iinal temperature in the retort may, with care, be increased to approximately 1200o F., but

temperatures above this point are neither y necessary nor advisable. Ifdesired, and it is usually preferable, supplemental steam may be admitted to the stream of vapors through pipe 35. [is the vaporizing temperature is increased, the valve 29 is closed more and more so that the pressure in the system,v

including both the still 1 and the retort-coil 25 is increased as the vaporizing and cracking temperatures are raised. The pressure may be increased lin increments of, say, twenty pounds per square inch after a pressure of forty'pounds is applied, until the pressure reaches the desired maximum.

With a temperature of 800 F. in the vaporizing-still and a temperature of about 1000o F. in the retort, this maximum pressure may.

be about eighty pounds per square inch.

The pressure may run as high as one hundred pounds per square inch, or even higher, but such high pressures have not'been found necessary.

During this high-temperature vaporization no substantial amount of decomposition takes place in the still 1. .This is due partly 'L to the pressure in the still and partly to the combination 0f the steam-jets acting against y the still which also causes local agitation of the oil and the vigorous agitation produced by the rotation of the agitator 13. By this combined arrangement, it is almost impossible for a particle of oil to remain in contact with the surface of the still long enough to become cracked. The particles get just'heat enough to vaporize them and the vapors are carried immediately to the space above the oil-level, there mixed withy steam and are then swept on through the retort 25. Substantially no carbon 1s formed in the vaporizing-still, therefore,

and even if a small amount was produced,

it would be harmless as the steam-jets and y the agitator would in their combined action maintain the particlesof carbon in suspension and away from the metal of the still. It has been found that the combination of the two is essential. If the agitator is omitted, the steam-jets would not be sufficient to agtate the heavy oil'and especially the residuum occurring toward the latter part of rlhe paddle-wheelv is not alone suiicient to prevent the formation of the gummy film on the still-bottom. rhis gummy residue vis much like glue in its nature and if` allowed to settle on the bottom would soonv form an incrustation which would cause buckling and burning-out of the' still. If both means are not employed, the heating-@dect would in a s time beco so diminished that it is impossible to distill off more than one-third of the still contents if pressure is present. Any attempt to distill a further amount would cause buckling and incrustation. On the contrary, if the lcombination of the steam-jets and paddleagitator is used, it becomes quite possible to distill oit as much as seventv-ive per cent of the oil in the still. Enough oil is then left to amply protect the bottom of the still.

If the starting-material isl crude-oil containing gasoline andv other low-boiling hydrocarbons, the oil may be run into the still While the latter is cold. The oil and still can then be gradually heated up together. The distilling off of the fractions boiling below, say, 400 F. takes place under atmospheric pressure and the vapors are conveyed directly to the condenser 31 through pipe 36, valve 37 being now open, and valve 34 closed. If'the furnace 26 is being heated, a small quantity of steam may be allowed to flow into and through the coil 25 from steam-inlet pipe 35, to prevent burning-out 0f the pipes of the retort. During this simple, low-temperature distillation just enough steam is admitted through the perforated pipe 20 to cause a little agitation. 1t. is not necessary then to operate the mechanical agitator 13. As the boiling-point of the oil becomes higher, the temperature is raised and the steam-pressure is increased. l/Vhen the gasoline-cut is completed, valve 37 is closed, valve 34 controlling the passage to the retort is opened and the temperature of the still is gradually increased. Furnace 26 has been heated up meanwhile and the vapors passing through the retort 25 are cracked in the manner hereinbefore described. Valve 29 is closed little by little to effect the proper Working-pressure throughout the system, the final pressurebeing preferably about eighty pounds per square inch when the temperature of the oil in the still reaches, say, 800O F. As soon as the pressure is applied and the vaporizing temperature raised above that of the gasoline-cut, the agitator 13 is set in motion and the flow of steam through the perforated pipes 20, 23,

lis increased. As in the treatment of the middle-distillates, additional steamv may be admitted to the retort-coil, with the oil vapors, through pipe 35. r1`he conditions of operation of this `cracking process are precisely those set forth for the treatment of middle-distillates, so that no further description thereof is thought necessary.

By the use of the method and apparatus hereindescribed. the temperature at which vaporization takes place during the cracking-step can be maintained very high so that the oil is readily vaporized, Without incidental decomposition ofthe oil in the still and theformation of troublesome carbon.

Such decomposition does not take place until the vapors reach the retort 25 and any carbon therein formed is swept along by the current of vapors beyond the regulatingvalve 29 and into the enlarged pressure-relieving pipe or chamber 30 Where it is deposited and from which it can be readily removed.

ll claim:-

1. The process of converting oils into lower-boiling hydrocarbons, which consists in heating in a still a relatively large quantity of oil, to vaporize it, under pressure, at a cracking temperature, introducing steam under pressure into and vigorously agitating the oil to prevent any substantial cracking thereof, then passing the vapors through a cracking-zone at a velocity suflicient to prevent substantial deposition of carbon and under substantially the same pressure as that employed in the vaporizing-step, then releasing the pressure upon the cracked vapors thereby causing the entrained carbon to becomedeposited and linally condensing the condensable vapors. I

2. The process of converting oils into lower-boiling hydrocarbons, which consists in'heating in a still a relatively large quantity of oil, to vaporize it, under pressure, at a cracking temperature, introducing steam under pressure into and vigorously agitating the oil to prevent any substantial cracking thereof, introducing steam into the vapors and passing the vapors thus mixed with steam through a. cracking-zone at a velocity sufficient to prevent substantial deposition of carbon and under substantially the same pressure as that employed in the vaporizingstep, then releasing the pressure upon the cracked vapors thereby causing the entrained carbon to become deposited and finally condensing the condensable vapors.

3. The process of converting oils into lower-boiling hydrocarbons, which consists in heating in a still a relatively large quantity of oil, to vaporize it. under a pressure of from 410 tor 100 pounds per square inch and at a cracking temperature of 700O F. to 850o F., introducing steam under pressure into and vigorously agitating the oil to prevent any substantial cracking thereof. then passing the vapors through a cracking-Zone maintained at a temperature of from 850o F. to 1200o F., at a velocity suiiicient to prevent substantial deposition of carbon and under substantially the same pressure as that employed in the vaporizing-step, then releasing the pressure upon the cracked vapors thereby causing the entrained carbon to become deposited and finally condensing the Condensable vapors.

1n testimony whereof, 1 affix my signature.

WllLLlAM T. BRYANT. 

